The package in question supports 3.4 as the newest Python version. 3.4 will be removed soon. Please test it against 3.5 & 3.6.
Python support has been dropped in Gnome Commander 1.8.1. If the version bump is done (or after going stable, this is up to you), we can mark this bug here as obsolete.
Meanwhile Gnome Commander 1.8.1 made it into the portage tree, without python dependency anymore. Because of this I would consider this issue as obsolete now.